Is it a pulled hamstring?
Based on the symptom that you notice when you try to run it is possible that you could have pulled the hamstring. If it is pulled you can try applying a heating pad to the area to see if that helps some of the pain, but I would recommend checking with your regular doctor as well to see what they say. However, even before doing that I would recommend letting your mom know what’s going on so that she can help you keep an eye on it (depending on the age).
